Institutes of Brain Science, Institute of Neurobiology and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China.
Neurobiol Dis. 2011 Aug;43(2):455-64. doi: 10.1016/j.nbd.2011.04.019. Epub 2011 Apr 30.
Glaucoma, mainly caused by high intraocular pressure (IOP), is characterized by apoptotic death of retinal ganglion cells (RGCs). We investigated the possible involvement of cyclin-dependent kinase 5 (Cdk5) and its activator p35, which have been implicated in a variety of neurological disorders, in RGC apoptosis in a rat experimental glaucoma model reproduced by blocking episcleral veins. Cholera toxin B subunit (CTB) retrogradely labeled RGCs displayed a dramatic reduction in number both in the central and peripheral retina on day 14 (D14) (P<0.05 vs. control), D21 (P<0.01 vs. control) and D28 (P<0.001 vs. control) after operation. Terminal dUTP nick end labeling (TUNEL)-positive cells were detected on D14 both in the central and peripheral regions, and numerous TUNEL-positive cells were found on D21 and D28 in both the regions (P all<0.001 vs. control). As compared with the control eyes, the expression level of Cdk5 was significantly increased on D21 (P<0.001), whereas that of p35 displayed a marked increase on D14 (P<0.01) and D21 (P<0.001). Meanwhile, both NR2A and p-NR2A(S1232) increased from D14 onwards (P<0.01 to 0.001). Co-immunoprecipitation indicated a direct interaction between Cdk5 and p-NR2A(S1232). Intraperitoneal injection of the Cdk5 inhibitor roscovitine remarkably inhibited RGC apoptosis (P<0.001 vs. vehicle group) and increased the number of CTB-labeled RGCs (P<0.05 to 0.01 vs. vehicle group) in whole flat-mounted retinas, which was accompanied by a significant decrease in expression levels of p35 and p-NR2A(S1232) (P all<0.01 vs. vehicle group). Our results suggest that elevation of p-NR2A(S1232) by Cdk5/p35 contributes to RGC apoptotic death in experimental glaucoma rats, which could be effectively ameliorated by inhibiting Cdk5/p35.
青光眼主要由眼内压（IOP）升高引起，其特征是视网膜神经节细胞（RGC）的凋亡死亡。我们研究了周期蛋白依赖性激酶 5（Cdk5）及其激活剂 p35 在通过阻断巩膜静脉复制的大鼠实验性青光眼模型中 RGC 凋亡中的可能作用，p35 已被牵涉到多种神经病变中。霍乱毒素 B 亚单位（CTB）逆行标记的 RGC 在术后第 14 天（D14）（与对照组相比，P<0.05）、第 21 天（D21）（与对照组相比，P<0.01）和第 28 天（D28）（与对照组相比，P<0.001）在中央和周边视网膜的数量均显著减少。在中央和周边区域均在 D14 检测到末端脱氧核苷酸转移酶（TUNEL）阳性细胞，在这两个区域在 D21 和 D28 均发现大量 TUNEL 阳性细胞（均 P<0.001 与对照组相比）。与对照组相比，Cdk5 的表达水平在 D21 时显著增加（P<0.001），而 p35 的表达水平在 D14 时明显增加（P<0.01）和 D21 时增加（P<0.001）。同时，NR2A 和 p-NR2A（S1232）从 D14 开始增加（P<0.01 至 0.001）。免疫共沉淀表明 Cdk5 与 p-NR2A（S1232）之间存在直接相互作用。腹腔内注射 Cdk5 抑制剂罗克洛维汀可显著抑制 RGC 凋亡（与载体组相比，P<0.001），并增加整个平置视网膜中 CTB 标记的 RGC 数量（与载体组相比，P<0.05 至 0.01），同时显著降低 p35 和 p-NR2A（S1232）的表达水平（均 P<0.01 与载体组相比）。我们的结果表明，Cdk5/p35 升高的 p-NR2A（S1232）导致实验性青光眼大鼠 RGC 凋亡死亡，通过抑制 Cdk5/p35 可有效改善。
